Conventionally, there is a demand for reading information on a surface of an object in a non-contact manner, and a device to which optical reflection has been applied is particularly known. Examples thereof are a barcode reading device, a QR code (registered trademark) reading device, a facsimile reading device, a rotary encoder, and a linear encoder.
Such a device has been used in various fields since it does not cause wear damage of the object due to the non-contact reading and is excellent in durability due to the optical type.
However, there are recently raised more market demands for size reduction of the device, high-resolution of information to be read, reduction of production cost, and the like.
In a conventional optical information-reading element 60, a light-emitting element 61 and a light-receiving element 62 are arranged on the same plane with a substrate 63 as illustrated in FIG. 8. Light (outgoing light 65a) from the light-emitting element 61 is reflected on a read object 64 (a reflecting part) and returns to the light-receiving element 62 as reflecting light 67 (returning light), and the outgoing light 65a and the returning light 67 are not parallel and generate a reflecting angle θ at the time of reflection. To irradiate the read object 64 with the outgoing light 65a and guide the returning light 67 into the light-receiving element 62 in this configuration, the light-emitting element 61 and the light-receiving element 62 need to be provided with lenses (refractive lenses) refracting the outgoing light 65a and the returning light 67 as much as the reflecting angle θ or need to be inclined as much as the angle θ against the plane of the substrate 63.
Providing the refractive lenses naturally requires cost of the refractive lenses, which is contrary to cost reduction. Inclining the light-emitting element 61 and the light-receiving element 62 against the plane of the substrate 63 as an alternative method requires a dedicated jig, an inspection device, and adjustment man-hours at the time of production, which is similarly contrary to cost reduction.
In addition, a distance h between the plane of the substrate 63 and the read object 64 needs to be longer than a dimension of each refractive lens, which is not favorable for size reduction, and when size reduction cannot be achieved, it is natural that high-resolution information cannot be read.
Further, since the light-emitting element 61 and the light-receiving element 62 are fixed at the time of production, a distance d between the light-emitting element 61 and the light-receiving element 62 cannot be changed. For this reason, the reflecting angle θ needs to be constant. To do so, the distance h must be a fixed value, and it is difficult to change the distance h flexibly.
Also, in a case in which the distance d is reduced for size reduction by providing small-sized lenses or inclining the light-emitting element 61 and the light-receiving element 62 against the plane of the substrate 63 without consideration of cost, a problem occurs in which part of the outgoing light 65a from the light-emitting element 61 directly reaches the light-receiving element 62 as outgoing light 65b. To solve this problem, a method of providing the light-emitting element 61 and the light-receiving element 62 with directional objects (lenses which are different from the aforementioned refractive lenses) to restrict directions of the outgoing light 65a and the returning light 67 or a method of providing a light shielding wall between the light-emitting element 61 and the light-receiving element 62 is needed. This causes a further increase in cost.